The invention relates generally to equipment used in oil exploration and more particularly to a system and method for repairing certain types of cables used in oil exploration and related industries by splicing together to undamaged sections of cable.
Production of oil and other hydrocarbon resources involves not only drilling wells to retrieve these resources, but also surveying potential productive fields to determine where wells should be drilled. Seismic surveys provided one means for determining whether or not a particular field contains hydrocarbon reserves. Equipment has been developed to conduct seismic surveys both on land and in offshore environments.
One type of equipment which is used in offshore seismic surveys uses pneumatic guns to generate shockwaves which are propagated through the water to the ocean floor and then through the underlying geological structure. The reflections of these shockwaves are then measured and analyzed to determine whether the geological structure below the ocean floor contains hydrocarbon reserves.
The pneumatic guns which are used in this type of offshore seismic survey are connected to a cable which is towed by a surface ship. The cable has an air line for providing compressed. air to the pneumatic guns, as well as a number of electrical wires for controlling the operation of the guns and returning collected data to the surface ship. Typically, several of the pneumatic guns are connected to a single cable. A single ship may tow several cables, each of which has a number of pneumatic guns connected to it.
Referring to FIG. 1, a cutaway view of a cable which is typical of those used in this field is shown. Cable 10 has a central conduit, or air line, 12 through which compressed air it is provided to the pneumatic guns. Conduit 12 is surrounded by a plurality of electrical wires 14. These wires are normally individual insulated wires, although other types of wires may be used. A protective sheath 16 surrounds electrical wires 14 to provide protection from wear which might cause short-circuits or other electrical problems. Sheath 16 is surrounded by a plurality of spring steel wires 18. In contrast to electrical wires 14, steel wires 18 are used to strengthen the cable, which in normally used must withstand several thousand pounds of tensile stress. Finally, an outer protective cover 20 encloses spring steel wires 18. A typical cable has a diameter of approximately 2.5 inches (6.35 cm).
As mentioned above, these cables are used to two pneumatic guns behind seismic survey ships. The cables are subjected to the harsh conditions of marine environments and, as result, will experience wear simply from normally used. Additionally, the cables may encounter obstacles such as fishing nets or debris which cause further wear. Still further, the cables may be kinked when they are reeled onto the ship or may be otherwise misused by the operators of the ship. Due to this wear and tear, cables may suffer damage (e.g., cut electrical lines or leaks in the air line) which renders them unusable.
The cables described above are quite expensive. It is not unusual for a single cable to cost in excess of $100,000. Despite the cost of these cables, however, damaged cables are typically replaced rather than repaired because there are no adequate means in the prior art to perform the repairs. It would therefore be desirable to provide a system and/or method for repairing damaged cables and thereby saving the cost of having to purchase a replacement cable.